Observations on Cellular Structures of Porphyridium cruentum

The cellular structure of Porphyridium cruentum was studied with both light and electron microscope. The photosynthetic plastid in this red alga was found to be structurally similar to that in the Chlorophyceae and higher green plants. The phycobilins, as well as the chlorophyll, seem to be associated with the lamellae of the plastid. The pyrenoid, a region of low lamellar density, contains no tubules, and does not appear to function in synthesis or storage of reserve material. Grains of floridean starch are located in the cytoplasm, outside the plastid. Typical mitochondrial organelles were not observed. The nucleus is eccentric, and contains a nucleolus located on the inner face of the nucleus, nearest the plastid. The schedule for staining the nucleus is given in detail. Other cell structures (sheath, dictyosomes, etc.) are described. Growing cells in light of intensity leads to disruption of the parallel arrangement of the lamellar characteristic of cells grown in moderate light.     

Observations on cellular structures of Porphyridium cruentum

The cellular structure of Porphyridium cruentum was studied with both light and electron microscope. The photosynthetic plastid in this red alga was found to be structurally similar to that in the Chlorophyceae and higher green plants. The phycobilins, as well as the chlorophyll, seem to be associated with the lamellae of the plastid. The pyrenoid, a region of low lamellar density, contains no tubules, and does not appear to function in synthesis or storage of reserve material. Grains of floridean starch are located in the cytoplasm, outside the plastid. Typical mitochondrial organelles were not observed. The nucleus is eccentric, and contains a nucleolus located on the inner face of the nucleus, nearest the plastid. The schedule for staining the nucleus is given in detail. Other cell structures (sheath, dictyosomes, etc.) are described. Growing cells in light of intensity leads to disruption of the parallel arrangement of the lamellar characteristic of cells grown in moderate light.     

The Mass Culture of Porphyridium cruentum

A study was made of the effect of temperature, detention period, light intensity, and salinity on the growth rate and over-all light energy conversion efficiency of Porphyridium cruentum cultured on a medium consisting of concentrated sea water and sewage enriched with urea, chelated iron, and other additives. It was found that the optimal temperature was within the range of 21 to 26 C. Growth was retarded at temperatures less than 13 C, and completely inhibited above 31 C. Over-all light energy conversion efficiency increased from 2.24% at the 4-day detention period to 2.76% at the 10-day period. Conversion efficiency ranged from 5.8% at a light energy absorption rate of 8.2 cal:liter:min to 2.3% at 35 to 39 cal:liter:min.

At salt concentrations less than 3.5%, Porphyridium could not successfully compete with other algae in open cultures. Salt concentrations as high as 4.6% had no inhibitory effect on its growth.

In studies on nutrition, it was found that growth on a medium of salts used in formulating synthetic sea water dissolved in sewage was equal to that on a control medium consisting of concentrated sea water and sewage (see above). They showed that sewage contains a substance or substances essential for optimal growth. Vitamin B₁₂ alone could not substitute for it.

     

紫外线对紫球藻的生物学效应

采用紫外线辐照紫球藻,处理剂量分别为10s、20s、30s、60s、90s、120s和180s。结果表明,10s剂量对紫球藻有促长作用,20s及30s对藻细胞生长和各项生理生化指标影响不显著,30s以上处理对其生长以及代谢产物的合成与分泌有抑制作用,且照射时间越长,抑制越强烈,紫球藻对紫外线的耐受极限为120s。结果还表明,高剂量(20~90s)照射能增加单细胞代谢产物含量;经紫外线辐照后的藻细胞第二代培养物在生长速度、叶绿素a含量、胞外多糖和β-胡萝卜素产量等与对照组相似。     

Method for B-phycoerythrin purification from Porphyridium cruentum

Summary Porphyridium cruentum extract was treated with rivanol for the precipitation and elimination of the polysaccharide typical for this alga, while all phycobiliproteins remained solubilized. After their precipitation with ammonium sulphate, B-phycoerythrin was differentially separated from the other phycobiliproteins, and rivanol was removed by Sephadex G-25 gel filtration. The purity of B-phycoerythrin was proved.Abbreviations B-PE B-phycoerythrin - b-PE b-phycoerythrin - R-PC R-phycocyanin - APC allophycocyanin - PBP phycobiliproteins     

Phycobilisome Structure of Porphyridium cruentum: POLYPEPTIDE COMPOSITION

Purified phycobilisomes of Porphyridium cruentum were solubilized in sodium dodecyl sulfate and resolved by sodium dodecyl sulfate-acrylamide gel electrophoresis into nine colored and nine colorless polypeptides. The colored polypeptides accounted for about 84% of the total stainable protein, and the colorless polypeptides accounted for the remaining 16%. Five of the colored polypeptides ranging in molecular weight from 13,300 to 19,500 were identified as the α and β subunits of allophycocyanin, R-phycocyanin, and phycoerythrin. Three others (29,000-30,500) were orange and are probably related to the γ subunit of phycoerythrin. Another colored polypeptide had a molecular weight of 95,000 and the characteristics of long wavelength-emitting allophycocyanin. Sequential dissociation of phycobilisomes, and analysis of the polypeptides in each fraction, revealed the association of a 32,500 molecular weight colorless polypeptide with a phycoerythrin fraction. The remaining eight colorless polypeptides were in the core fraction of the phycobilisome, which also was enriched in allophycocyanin. In addition, the core fraction was enriched in a colored 95,000 dalton polypeptide. Inasmuch as a polypeptide with the same molecular weight is found in thylakoid membranes (free of phycobilisomes), it is suggested that this polypeptide is involved in anchoring phycobilisomes to thylakoid membranes.     

超声波降解紫球藻胞外多糖研究

通过测定溶液粘度,判断超声波降解紫球藻(Porphyridium cruentumi)胞外多糖的效果。运用均匀设计对超声波降解紫球藻胞外多糖的影响因素(处理振幅、时间、脉冲)进行优化,获得超声波处理的最佳条件:振幅39%、处理时间245s和脉冲9.5s。在最佳条件下,胞外多糖的粘度为2.98mm²/s,与预测值一致。采用DPS软件对实验结果进行二次多项式分析与拟合,并对模型和回归系数进行显著性检验,建立了以胞外多糖粘度为目标的回归方程式。     

Evaluation of the protein quality of Porphyridium cruentum

The amino acid profile of the red microalga Porphyridium cruentum and its protein extract have been determined in order to assess the nutritional quality of this biomass for human consumption. Total protein determined by elemental analysis represented 56 % of its dry weight. Hydro-soluble proteins extracted at pH 12 and 40 °C were analysed by the Lowry method giving 47 %, which represented 84 % of total protein per dry weight. The amino acid sequence of the biomass and the protein extract was composed of a set of essential (39 % for the former and 37 % for the latter) and non-essential amino acids (61 % for the former and 63 % for the latter) that compares favourably with the standard protein/amino acid requirements proposed by Food and Agricultural Organisation and World Health Organisation.     

Noncovalent Intermolecular Forces in Phycobilisomes of Porphyridium cruentum

Using sensitized fluorescence as a measure of intactness of phycobilisomes isolated from Porphyridium cruentum, the effects of various environmental perturbations on phycobilisome integrity were investigated. The rate of phycobilisome dissociation in 0.75 ionic strength sodium salts proceeds in the order: SCN⁻ > NO₃⁻ > Cl⁻ > C₆H₅O₇³⁻ > SO₄²⁻ > PO₄³⁻, as predicted from the lyotropic series of anions and their effects on hydrophobic interactions in proteins. Similarly, increasing temperature (to 30 C) and pH values approaching the isoelectric points of the biliproteins stabilize phycobilisomes. Deuterium substitution at exchangeable sites on the phycobiliproteins decreases the rate of phycobilisome dissociation, while substitution at nonexchangeable sites increases rates of dissociation. It is concluded that hydrophobic intermolecular interactions are the most important forces in maintaining the phycobilisome structure. Dispersion forces also seem to contribute to phycobilisome stabilization. The adverse effects of electrostatic repulsion must not be ignored; however, it seems that the requirement of phycobilisomes of high salt concentrations is not simply countershielding of charges on the proteins.     

Phycobilisomes of Porphyridium cruentum. I. Isolation

A procedure was developed for the isolation of phycobilisomes from Porphyridium cruentum. The cell homogenate, suspended in phosphate buffer (pH 6.8), was treated with 1% Triton X-100, and its supernatant fraction was centrifuged on a sucrose step gradient. Phycobilisomes were recovered in the 1 M sucrose band. The phycobilisome fraction was identified by the characteristic appearance of the phycobilisomes, and the absorbance of the component pigments: phycoerythrin, R-phycocyanin, and allophycocyanin Isolated phycobilisomes had a prolate shape, with one particle axis longer than the other. Their size varied somewhat with their integrity, but was about 400–500 A (long axis) by 300–320 A (short axis). Phycobilisome recovery was determined at six phosphate buffer concentrations from 0.067 M to 1.0 M. In 0.5 M phosphate, phycobilisome yield (60%) and preservation were optimal. Such a preparation had a phycoerythrin 545 nm/phycocyanin 620 nm ratio of 8.4. Of the detergents tested (Triton X-100, Tween 80, and sodium deoxycholate), Triton X-100 gave the best results Freezing of the cells caused destruction of phycobilisomes.     

Properties and Ultrastructure of Phycoerythrin From Porphyridium cruentum

Phycoerythrin, a photosynthetic accessory pigment, was isolated from Porphyridium cruentum and examined by electron microscopy and disc gel electrophoresis. The absorption monomer, with maxima at 563, 545, and a shoulder at 500 nm, has a molecular weight of about 300,000. With phosphotungstic acid staining it appears as a tightly structured disc-shaped particle possessing a mean diameter of 101 ± 0.4Ä and height of 54 ± 0.7Å. The absorption maxima remained the same in glutaraldehyde fixed material, and in dimer and trimer aggregates. Treatment with sodium dodecyl sulfate caused a breakdown into smaller units accompanied by a loss of the 563 nm peak. It is suggested that this absorption monomer is the in vivo functional species and comparable to the phycocyanin hexamer, but structurally distinguishable at the ultrastructural level. It has been calculated that about 35 phycobiliprotein molecules can be contained within each phycobilisome. There are 1.4 × 10³ chlorophyll molecules per phycobilisome, but not contained within it.     

Effects of agitation on the microalgae Phaeodactylum tricornutum and Porphyridium cruentum

The effect of mechanical agitation on the microalgae Phaeodactylum tricornutum and Porphyridium cruentum was investigated in aerated continuous cultures with and without the added shear protectant Pluronic F68. Damage to cells was quantified through a decrease in the steady state concentration of the biomass in the photobioreactor. For a given aeration rate, the steady state biomass concentration rose with increasing rate of mechanical agitation until an upper limit on agitation speed was reached. This maximum tolerable agitation speed depended on the microalgal species. Further increase in agitation speed caused a decline in the steady state concentration of the biomass. An impeller tip speed of >1.56 m s^–1 damaged P. tricornutum in aerated culture. In contrast, the damage threshold tip speed for P. cruentum was between 2.45 and 2.89 m s^–1. Mechanical agitation was not the direct cause of cell damage. Damage occurred because of the rupture of small gas bubbles at the surface of the culture, but mechanical agitation was instrumental in generating the bubbles that ultimately damaged the cells. Pluronic F68 protected the cells against damage and increased the steady state concentration of the biomass relative to operation without the additive. The protective effect of Pluronic was concentration-dependent over the concentration range of 0.01–0.10% w/v.     

紫球藻及其胞外多糖对小鼠免疫功能的调节作用

探讨紫球藻及其胞外多糖对免疫低下小鼠免疫功能的调节作用,用环磷酰胺(CY)建立昆明种小鼠免疫功能低下的实验模型。小鼠随机均分6组,其中2组每天分别给予紫球藻藻粉1200、600 mg/kg灌胃,2组给予紫球藻胞外多糖300、150 mg/kg灌胃,正常对照组及CY组用等容积生理盐水灌胃,连续14 d。实验结果表明紫球藻及其胞外多糖均可显著提高免疫抑制小鼠的脾指数、胸腺指数、碳廓清能力、单核细胞吞噬功能,并可对抗环磷酰胺引起的外周血白细胞数目下降,因此紫球藻藻粉及其胞外多糖对小鼠免疫功能具有一定的正向调节作用。毒性实验表明,小鼠腹腔注射300、150 mg/kg紫球藻胞外多糖溶液和分别给予紫球藻藻粉1200、600 mg/kg灌胃,小鼠未出现死亡,也未有明显毒性反应出现的一些指标变化,说明紫球藻藻粉及胞外多糖的安全性较高。     

Gewinnung und Anwendung von Phycoerythrin aus Porphyridium cruentum

Durch Bestrahlung einer Kultur von Porphyridium cruentum mit Licht, das vorher eine Kultur von Chlorella vulgaris passiert hat, läßt sich sowohl der Grad der Lichtnutzung der Algen als auch die Phycoerythrinbildung pro Rotalgenzelle (bis zu ca. 50 %) im Vergleich zu weißem Licht steigern. Unter den hier gewählten Versuchsbedingungen erwies sich eine Nitratkonzentration von 1,2 g 1⁻¹ im Medium als die geeignetste für die Bildung von B-Phycoerythrin.Durch Zellaufschluß mit Ultraschall und Reinigung mit verschiedenen Chromatografie-Techniken läßt sich ein B-Phycoerythrinpräparat isolieren.Mit dem erhaltenen Produkt wurden über das Biotin-Streptavidin-System Fluoreszenzmarkierungen an Latexpartikeln und Sproßnarben von Hefezellen vorgenommen.     

Isolation and Function of Allophycocyanin B of Porphyridium cruentum

Allophycocyanin B was purified to homogeneity from the eukaryotic red alga Porphyridium cruentum. This biliprotein is distinct from the allophycocyanin of P. cruentum with respect to subunit molecular weights, and spectroscopic and immunological properties. The purified allophycocyanin B has a long wavelength absorption maximum at 669 nm at room temperature and at 675 nm at −196 C while the fluorescence emission maximum is at 673 nm at room temperature and 679 nm at −196 C. The emission spectrum of allophycocyanin shifted only 1 nm, from 659 to 660 nm, on cooling to −196 C, and was the same with allophycocyanin crystals as it was with pure solutions of the pigment. Phycobilisomes from P. cruentum have a major fluorescence emission band at 680 nm at −196 C which emanates from the small amount of allophycocyanin B present in the phycobilisomes. Light energy absorbed by the bulk of the biliprotein pigments is transferred to allophycocyanin B with high efficiency.     

Effects of nitrogen on growth and carbohydrate formation in Porphyridium cruentum

The microalga Porphyridium cruentum (Rhodophyta) has several industrial and pharmaceutical uses, especially for its polysaccharide production. This study aimed to investigate the influence of nitrogen levels as reflected by altered N:P ratios on the production and content of biomass and carbohydrate. N:P molar ratios were altered in batch cultures to range from 1.6 to 50 using the Redfield ratio of 1:16 as reference. Algal growth (estimated as final cell number, biomass concentration and maximum specific growth rate) was negatively affected at low N:P ratios. The optimal N:P ratio for growth was identified at 35–50, with specific growth rates of 0.19 day^?1 and maximum cell concentrations of 59·10⁸ cells L^?1 and 1.2 g dry weight of biomass L^?1. In addition, variation in cell size was seen. Cells with larger diameters were at higher N:P ratios and smaller cells at lower ratios. The cellular carbohydrate content increased under reduced nitrogen availability. However, because accumulation was moderate at the lowest N:P ratio, 0.4 g per g dry weight biomass compared to 0.24 at the Redfield ratio of 16:1, conditions for increased total carbohydrate formation were identified at the N:P ratios optimal for growth. Additionally, carbohydrates were largely accumulated in late exponential to stationary phase.     

Recovery of pure B-phycoerythrin from the microalga Porphyridium cruentum.

Phycoerythrin is a major light-harvesting pigment of red algae and cyanobacteria that is widely used as a fluorescent probe and analytical reagent. In this paper, B-phycoerythrin and R-phycocyanin in native state, from the red alga Porphyridium cruentum were obtained by an inexpensive and simple process. The best results of this purification procedure were scaled up by a factor of 13 to a large preparative level using an anionic chromatographic column of DEAE cellulose. Gradient elution with acetic acid-sodium acetate buffer (pH 5.5) was used. In these conditions both 32% of B-phycoerythrin and 12% of R-phycocyanin contained in the biomass of the microalgae was recovered. B-phycoerythrin was homogeneous as determined by sodium dodecyl sulfate-poly-acrylamide gel electrophoresis (SDS-PAGE), yielding three migrating bands corresponding to its three subunits, consistent with the (alpha beta)(6)gamma subunit composition characteristic of this biliprotein and the spectroscopic characterization of B-PE (UV-visible absorption and emission spectroscopy; steady-state and polarization fluorescence), is accompanied. Finally, a preliminary cost analysis of the recovery process is presented.     

Arachidonic acid production by the red alga Porphyridium cruentum

The single-celled alga, Porphyridium cruentum, was assessed by means of chromatographic separation and mass spectral analysis of its fatty acids to be a potentially competetive source of arachidonic (5,8,11,14-eicosatetraenoic) acid. Models for both cell growth and production of the prostaglandin precursor at various temperatures and light intensities are presented. Increasing the light intensity within the range 1700-8000 lux increases the cell growth rate without affecting the arachidonic acid yield per cell; increasing the cultivation temperature from 18 degrees C to ca. 32 degrees C lowers the yield of arachidonic acid per cell but increases the rate of its production per unit volume and time. The increase of the weight ratio of arachidonic:palmitic acids at low temperatures is interpreted as a means of controlling the microviscosities of cellular membranes. In addition, the arachidonic acid content of cells decreases with the culture's age, despite increases in unit cell dry weight. The maximum rate of 0.46 mg arachidonic acid L(-1) h(-1) was calculated by means of the model to occur at ca. 32 degrees C and 8000 lux in liquid cultures of 12 x 10(9) cells/L. Estimates of the cost of producing arachidonic acid by means of this alga range from $0.15/g to $1.00/g of arachidonic acid. Cells grown at 18 degrees C in the presence of 0.3% linoleic acid swelled and produced gorlic (13-cyclopent-2-enyltridec-6-enoic) acid and another compound not normally observed. An estimated threefold increase of arachidonic acid content also occurred, but no significant lipogenesis was induced at 23 degrees C in the presence of 1% kerosene or 0.3% palmitic, stearic, oleic, or linoleic acids.